Heaven supposedly is a place where there is no suffering. But to exist in any particular form or place, be this human or Earth, angel or Paradise, is necessarily to suffer, to bear, the limitations of being in said form or place. Therefore a suffering-free heaven can’t exist.
One may argue that the totality of existence could qualify as heaven because the entirety could suffer no limitations on what it is, and just such a flawless state awaits one in the afterlife. But one can’t exist as a perfect entirety and still be an identifiable one. Thus any such pan-existence heaven can’t be awaiting one’s personal arrival.
But if one, limited yet unique as an entity, understands suffering as pressure to evolve within a perfect totality, and truly appreciates the temporary yet miraculous opportunity to make progress, isn’t one already in heaven?